1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device, and more particularly relates to a semiconductor device having a semiconductor element in which wire bonding is applied in or between semiconductor elements, and to a method of manufacturing the semiconductor device.
2. Description of the Related Art
Conventionally, there have been semiconductor devices using a semiconductor element in which a plurality of semiconductor elements (chips) are mounted in a package, and methods of connecting such a plurality of chips by way of wire bonding (for example in Patent Document 1) have been proposed. In the method disclosed in Patent Document 1, when a plurality of chips are wire connected, firstly, a first wire is wedge bonded at a terminal of an electrode pattern onto an upper electrode of a chip. Next, a second wire is ball bonded on the wedge-bonded portion.
With this, the ball formed by the ball bonding is connected onto the upper electrode of the chip, so that the wire is prevented from becoming a thin film at this portion and thus the wire bonding strength is enhanced.
However, the method disclosed in Patent Document 1 presents a problem that when wedge bonding is performed directly on the electrode of a semiconductor element, stable bonding cannot be obtained due to the thinned thickness of the electrode. Further, in a case where a semiconductor element is of a type having positive and negative electrodes on one side, the height of the surface of one of the electrodes is lower than the height of the surface of the light emitting element. This leads to a problem that, when the wedge bonding is performed onto the one of the surface of the electrode, the surface of the step difference of the semiconductor element may be damaged by the tip portion of the capillary. Also, in the method described in Patent Document 1, ball bonding is performed on the wedge-bonded portion. Accordingly, the distance between the wedge bonding portion of the wire and the surface of the semiconductor element becomes small and there arises a problem in which heat dissipation efficiency of adjacent members etc., disposed between the wedge-bonded portion and the semiconductor element decreases.
As a solution to solve the problems, there is proposed that a top portion of the upper surface of the ball portion of the wire loop is pressed together with a part of the wire, and a wire loop is provided to bridge between the upper surface of the ball portion and the bonding surface (for example, in Patent Document 2). With this method, problems caused by such as degradation of wires, mutual contact of wires and/or short-circuiting of a wire can be prevented.
Patent Document 1: JP 2002-353267A
Patent Document 2: JP 2008-130863A